12 Testing

Automated testing is a key part of Grails. Hence, Grails provides many ways to making testing easier from low level unit testing to high level functional tests. This section details the different capabilities that Grails offers for testing.

Grails 1.3.x and below used the grails.test.GrailsUnitTestCase class hierarchy for testing in a JUnit 3 style. Grails 2.0.x and above deprecates these test harnesses in favour of mixins that can be applied to a range of different kinds of tests (JUnit 3, Junit 4, Spock etc.) without subclassing

The first thing to be aware of is that all of the create-* and generate-* commands create unit or integration tests automatically. For example if you run the create-controller command as follows:

grails create-controller com.acme.app.simple

Grails will create a controller at grails-app/controllers/com/acme/app/SimpleController.groovy, and also a unit test at test/unit/com/acme/app/SimpleControllerTests.groovy. What Grails won't do however is populate the logic inside the test! That is left up to you.

The default class name suffix is Tests but as of Grails 1.2.2, the suffix of Test is also supported.

You can force a clean before running tests by passing -clean to the test-app command.

Grails writes both plain text and HTML test reports to the target/test-reports directory, along with the original XML files. The HTML reports are generally the best ones to look at.

Using Grails' interactive mode confers some distinct advantages when executing tests. First, the tests will execute significantly faster on the second and subsequent runs. Second, a shortcut is available to open the HTML reports in your browser:

open test-report

You can also run your unit tests from within most IDEs.

Targeting Tests

You can selectively target the test(s) to be run in different ways. To run all tests for a controller named SimpleController you would run:

grails test-app SimpleController

This will run any tests for the class named SimpleController. Wildcards can be used...

grails test-app *Controller

This will test all classes ending in Controller. Package names can optionally be specified...

grails test-app some.org.*Controller

or to run all tests in a package...

grails test-app some.org.*

or to run all tests in a package including subpackages...

grails test-app some.org.**.*

You can also target particular test methods...

grails test-app SimpleController.testLogin

This will run the testLogin test in the SimpleController tests. You can specify as many patterns in combination as you like...

grails test-app some.org.* SimpleController.testLogin BookController

Targeting Test Types and/or Phases

In addition to targeting certain tests, you can also target test types and/or phases by using the phase:type syntax.

Grails organises tests by phase and by type. A test phase relates to the state of the Grails application during the tests, and the type relates to the testing mechanism.

Grails comes with support for 4 test phases (unit, integration, functional and other) and JUnit test types for the unit and integration phases. These test types have the same name as the phase.

Testing plugins may provide new test phases or new test types for existing phases. Refer to the plugin documentation.

To execute the JUnit integration tests you can run:

grails test-app integration:integration

Both phase and type are optional. Their absence acts as a wildcard. The following command will run all test types in the unit phase:

grails test-app unit:

The Grails Spock Plugin is one plugin that adds new test types to Grails. It adds a spock test type to the unit, integration and functional phases. To run all spock tests in all phases you would run the following:

grails test-app :spock

To run the all of the spock tests in the functional phase you would run...

grails test-app functional:spock

More than one pattern can be specified...

grails test-app unit:spock integration:spock

Targeting Tests in Types and/or Phases

Test and type/phase targetting can be applied at the same time:

grails test-app integration: unit: some.org.**.*

This would run all tests in the integration and unit phases that are in the package some.org or a subpackage.

12.1 Unit Testing

Unit testing are tests at the "unit" level. In other words you are testing individual methods or blocks of code without consideration for surrounding infrastructure. Unit tests are typically run without the presence of physical resources that involve I/O such databases, socket connections or files. This is to ensure they run as quick as possible since quick feedback is important.

The Test Mixins

Since Grails 2.0, a collection of unit testing mixins is provided by Grails that lets you enhance the behavior of a typical JUnit 3, JUnit 4 or Spock test. The following sections cover the usage of these mixins.

The previous JUnit 3-style GrailsUnitTestCase class hierarchy is still present in Grails for backwards compatibility, but is now deprecated. The previous documentation on the subject can be found in the Grails 1.3.x documentation

You won't normally have to import any of the testing classes because Grails does that for you. But if you find that your IDE for example can't find the classes, here they all are:

grails.test.mixin.TestFor

grails.test.mixin.Mock

grails.test.mixin.TestMixin

grails.test.mixin.support.GrailsUnitTestMixin

grails.test.mixin.domain.DomainClassUnitTestMixin

grails.test.mixin.services.ServiceUnitTestMixin

grails.test.mixin.web.ControllerUnitTestMixin

grails.test.mixin.web.FiltersUnitTestMixin

grails.test.mixin.web.GroovyPageUnitTestMixin

grails.test.mixin.web.UrlMappingsUnitTestMixin

grails.test.mixin.webflow/WebFlowUnitTestMixin

Note that you're only ever likely to use the first two explicitly. The rest are there for reference.

Test Mixin Basics

Most testing can be achieved via the TestFor annotation in combination with the Mock annotation for mocking collaborators. For example, to test a controller and associated domains you would define the following:

@TestFor(BookController)
@Mock([Book, Author, BookService])

The TestFor annotation defines the class under test and will automatically create a field for the type of class under test. For example in the above case a "controller" field will be present, however if TestFor was defined for a service a "service" field would be created and so on.

The Mock annotation creates mock version of any collaborators. There is an in-memory implementation of GORM that will simulate most interactions with the GORM API. For those interactions that are not automatically mocked you can use the built in support for defining mocks and stubs programmatically. For example:

Adding the TestFor annotation to a controller causes a new controller field to be automatically created for the controller under test.

The TestFor annotation will also automatically annotate any public methods starting with "test" with JUnit 4's @Test annotation. If any of your test method don't start with "test" just add this manually

To test the simplest "Hello World"-style example you can do the following:

The response object is an instance of GrailsMockHttpServletResponse (from the package org.codehaus.groovy.grails.plugins.testing) which extends Spring's MockHttpServletResponse class and has a number of useful methods for inspecting the state of the response.

For example to test a redirect you can use the redirectedUrl property:

Many actions make use of the parameter data associated with the request. For example, the 'sort', 'max', and 'offset' parameters are quite common. Providing these in the test is as simple as adding appropriate values to a special params variable:

You only need to do this though if the code under test uses the xhr property on the request.

Testing View Rendering

To test view rendering you can inspect the state of the controller's modelAndView property (an instance of org.springframework.web.servlet.ModelAndView) or you can use the view and model properties provided by the mixin:

The GrailsMockMultipartFile constructor arguments are the name and contents of the file. It has a mock implementation of the transferTo method that simply records the targetFileLocation and doesn't write to disk.

Testing Command Objects

Special support exists for testing command object handling with the mockCommandObject method. For example consider the following action:

The testing framework also supports allowing Grails to create the command object instance automatically. To test this invoke the no-arg version of the controller action method. Grails will create an instance of the command object, perform data binding on it using the request parameters and validate the object just like it does in when the application is runnning. See the test below.

Testing Calling Tag Libraries

You can test calling tag libraries using ControllerUnitTestMixin, although the mechanism for testing the tag called varies from tag to tag. For example to test a call to the message tag, add a message to the messageSource. Consider the following action:

Testing Custom Tags

The core Grails tags don't need to be enabled during testing, however custom tag libraries do. The GroovyPageUnitTestMixin class provides a mockTagLib() method that you can use to mock a custom tag library. For example consider the following tag library:

This will attempt to render a template found at the location grails-app/views/simple/_hello.gsp. Note that if the template depends on any custom tag libraries you need to call mockTagLib as described in the previous section.

Some core tags use the active controller and action as input. In GroovyPageUnitTestMixin tests, you can manually set the active controller and action name by setting controllerName and actionName properties on the webRequest object:

webRequest.controllerName = 'simple'
webRequest.actionName = 'hello'

12.1.3 Unit Testing Domains

Overview

The mocking support described here is best used when testing non-domain artifacts that use domain classes, to let you focus on testing the artifact without needing a database. But when testing persistence it's best to use integration tests which configure Hibernate and use a database.

Domain class interaction can be tested without involving a database connection using DomainClassUnitTestMixin. This implementation mimics the behavior of GORM against an in-memory ConcurrentHashMap implementation. Note that this has limitations compared to a real GORM implementation. The following features of GORM for Hibernate can only be tested within an integration test:

String-based HQL queries

composite identifiers

dirty checking methods

any direct interaction with Hibernate

However a large, commonly-used portion of the GORM API can be mocked using DomainClassUnitTestMixin including:

Simple persistence methods like save(), delete() etc.

Dynamic Finders

Named Queries

Query-by-example

GORM Events

If something isn't supported then GrailsUnitTestMixin's mockFor method can come in handy to mock the missing pieces. Alternatively you can write an integration test which bootstraps the complete Grails environment at a cost of test execution time.

The Basics

DomainClassUnitTestMixin is typically used in combination with testing either a controller, service or tag library where the domain is a mock collaborator defined by the Mock annotation:

Testing Constraints

Classes configured to be validateable via the grails.validateable.classes property in Config.groovy

The first 3 are easily testable in a unit test with no special configuration necessary as long as the test method is marked with TestFor or explicitly applies the GrailsUnitTestMixin using TestMixin. See the examples below.

For validateable classes which are not one of the first 3 types listed above but are configured with the grails.validateable.classes property in Config.groovy, one additional step is required to test validation. GrailsUnitTestMixin provides a method named mockForConstraintsTests that will mock validation support for these classes. See the example below.

Note that the mockForConstraintsTests method changes the behavior of the errors object such that something like book.errors'author' will evaluate to the name of the failed constraint, not a org.springframework.validation.FieldError object. This is convenient for unit tests. If your unit test really does want a reference to the org.springframework.validation.FieldError object use something like book.errors.getFieldError('author').

That's it for testing constraints. One final thing we would like to say is that testing the constraints in this way catches a common error: typos in the "constraints" property name which is a mistake that is easy to make and equally easy to overlook. A unit test for your constraints will highlight the problem straight away.

12.1.4 Unit Testing Filters

Unit testing filters is typically a matter of testing a controller where a filter is a mock collaborator. For example consider the following filters class:

This filter interceptors the list action of the simple controller and redirects to the book controller. To test this filter you start off with a test that targets the SimpleController class and add the CancellingFilters as a mock collaborator:

Note that the action parameter is required because it is unknown what the action to invoke is until the action is actually called. The controller parameter is optional and taken from the controller under test. If it is another controller you are testing then you can specify it:

withFilters(controller:"book",action:"list") {
controller.list()
}

12.1.5 Unit Testing URL Mappings

The Basics

Testing URL mappings can be done with the TestFor annotation testing a particular URL mappings class. For example to test the default URL mappings you can do the following:

Assert Reverse URL Mappings

You use assertReverseUrlMapping to check that correct links are produced for your URL mapping when using the link tag in GSP views. An example test is largely identical to the previous listing except you use assertReverseUrlMapping instead of assertForwardUrlMapping. Note that you can combine these 2 assertions with assertUrlMapping.

12.1.6 Mocking Collaborators

Beyond the specific targeted mocking APIs there is also an all-purpose mockFor() method that is available when using the TestFor annotation. The signature of mockFor is:

mockFor(class, loose = false)

This is general-purpose mocking that lets you set up either strict or loose demands on a class.

This method is surprisingly intuitive to use. By default it will create a strict mock control object (one for which the order in which methods are called is important) that you can use to specify demands:

Notice that you can mock static as well as instance methods by using the "static" property. You then specify the name of the method to mock, with an optional range argument. This range determines how many times you expect the method to be called, and if the number of invocations falls outside of that range (either too few or too many) then an assertion error will be thrown. If no range is specified, a default of "1..1" is assumed, i.e. that the method must be called exactly once.

The last part of a demand is a closure representing the implementation of the mock method. The closure arguments must match the number and types of the mocked method, but otherwise you are free to add whatever you want in the body.

Call mockControl.createMock() to get an actual mock instance of the class that you are mocking. You can call this multiple times to create as many mock instances as you need. And once you have executed the test method, call mockControl.verify() to check that the expected methods were called.

Grails mocks also provide a demandExplicit method that can be used in place of demand. This will check the mocked class's metaClass and throw an ExplicitDemandException if a method with that name and signature doesn't exist. For example, given the service:

Using demandExplicit should be the preferred method for mocking as it is more likely to catch issues when changing method signatures. Use demand when the method to be mocked is added dynamically, otherwise use demandExplicit.

Lastly, the call:

def looseControl = mockFor(MyService, true)

will create a mock control object that has only loose expectations, i.e. the order that methods are invoked does not matter.

12.1.7 Mocking Codecs

The GrailsUnitTestMixin provides a mockCodec method for mocking custom codecs which may be invoked while a unit test is running.

mockCodec(MyCustomCodec)

Failing to mock a codec which is invoked while a unit test is running may result in a MissingMethodException.

12.1.8 Unit Test Metaprogramming

If runtime metaprogramming needs to be done in a unit test it needs to be done early in the process before the unit testing environment is fully initialized. This should be done when the unit test class is being initialized. For a Spock based test this should be done in the setupSpec() method. For a JUnit test this should be done in a method marked with @BeforeClass.

12.2 Integration Testing

Integration tests differ from unit tests in that you have full access to the Grails environment within the test. Grails uses an in-memory H2 database for integration tests and clears out all the data from the database between tests.

One thing to bear in mind is that logging is enabled for your application classes, but it is different from logging in tests. So if you have something like this:

the "starting tests" message is logged using a different system than the one used by the application. The log property in the example above is an instance of java.util.logging.Logger (inherited from the base class, not injected by Grails), which doesn't have the same methods as the log property injected into your application artifacts. For example, it doesn't have debug() or trace() methods, and the equivalent of warn() is in fact warning().

Transactions

Integration tests run inside a database transaction by default, which is rolled back at the end of the each test. This means that data saved during a test is not persisted to the database. Add a transactional property to your test class to check transactional behaviour:

In the above case response is an instance of MockHttpServletResponse which we can use to obtain the generated content with contentAsString (when writing to the response) or the redirected URL. These mocked versions of the Servlet API are completely mutable (unlike the real versions) and hence you can set properties on the request such as the contextPath and so on.

Grails does not invoke interceptors or servlet filters when calling actions during integration testing. You should test interceptors and filters in isolation, using functional testing if necessary.

Testing Controllers with Services

If your controller references a service (or other Spring beans), you have to explicitly initialise the service from your test.

Grails auto-magically sees your call to signup() as a call to the action and populates the command object from the mocked request parameters. During controller testing, the params are mutable with a mocked request supplied by Grails.

Testing Controllers and the render Method

The render method lets you render a custom view at any point within the body of an action. For instance, consider the example below:

In the above example the result of the model of the action is not available as the return value, but instead is stored within the modelAndView property of the controller. The modelAndView property is an instance of Spring MVC's ModelAndView class and you can use it to the test the result of an action:

Simulating Request Data

You can use the Spring MockHttpServletRequest to test an action that requires request data, for example a REST web service. For example consider this action which performs data binding from an incoming request:

def create() {
[book: new Book(params.book)]
}

To simulate the 'book' parameter as an XML request you could do something like the following:

With JSON don't forget the class property to specify the name the target type to bind to. In XML this is implicit within the name of the <book> node, but this property is required as part of the JSON packet.

For more information on the subject of REST web services see the section on REST.

Here we have signaled to the flow to execute the event "go" which causes a transition to the "next" state. In the example a transition action placed a hello variable into the flow scope.

Testing Tag Libraries

Testing tag libraries is simple because when a tag is invoked as a method it returns its result as a string (technically a StreamCharBuffer but this class implements all of the methods of String). So for example if you have a tag library like this:

Testing Domain Classes

Testing domain classes is typically a simple matter of using the GORM API, but there are a few things to be aware of. Firstly, when testing queries you often need to "flush" to ensure the correct state has been persisted to the database. For example take the following example:

This test will fail because calling save does not actually persist the Book instances when called. Calling save only indicates to Hibernate that at some point in the future these instances should be persisted. To commit changes immediately you "flush" them:

In this case since we're passing the argument flush with a value of true the updates will be persisted immediately and hence will be available to the query later on.

12.3 Functional Testing

Functional tests involve making HTTP requests against the running application and verifying the resultant behaviour. The functional testing phase differs from the integration phase in that the Grails application is now listening and responding to actual HTTP requests. This is useful for end-to-end testing scenarios, such as making REST calls against a JSON API.

Grails does not ship with any support for writing functional tests directly, but there are several plugins available for this.

Common Options

There are options that are common to all plugins that control how the Grails application is launched, if at all.

inline

The -inline option specifies that the grails application should be started inline (i.e. like run-app).

This option is implicitly set unless the baseUrl or war options are set

war

The -war option specifies that the grails application should be packaged as a war and started. This is useful as it tests your application in a production-like state, but it has a longer startup time than the -inline option. It also runs the war in a forked JVM, meaning that you cannot access any internal application objects.

grails test-app functional: -war

Note that the same build/config options for the run-war command apply to functional testing against the WAR.

https

The -https option results in the application being able to receive https requests as well as http requests. It is compatible with both the -inline and -war options.

grails test-app functional: -https

Note that this does not change the test base url to be https, it will still be http unless the -httpsBaseUrl option is also given.

httpsBaseUrl

The -httpsBaseUrl causes the implicit base url to be used for tests to be a https url.

grails test-app functional: -httpsBaseUrl

This option is ignored if the -baseUrl option is specified.

baseUrl

The baseUrl option allows the base url for tests to be specified.

grails test-app functional: -baseUrl=http://mycompany.com/grailsapp

This option will prevent the local grails application being started unless -inline or -war are given as well. To use a custom base url but still test against the local Grails application you must specify one of either the -inline or -war options.

Copies of this document may be made for your own use and for distribution to others, provided that you do not charge any fee for such copies and further provided that each copy contains this Copyright Notice, whether distributed in print or electronically.
Sponsored by Pivotal